挤压加工对苦荞粉理化性质的影响

为了阐明挤压加工技术对苦荞粉理化性质的影响,分别研究了不同挤压温度、物料水分和螺杆转速对挤压苦荞粉的吸水性指数、水溶性指数、膨胀势、糊化及凝胶特性的影响规律。结果表明:与未挤压苦荞粉相比,经挤压改性后的苦荞粉在30℃水浴时有更好的吸水性和水溶性;在100℃水浴时的水溶性增大,吸水性减小;膨胀势、糊化特征值及凝胶特征值均明显升高。随挤压温度升高,挤压苦荞粉的峰值粘度、衰减值增大,谷值粘度、回生值降低,制成的凝胶品质更好;随物料水分升高,吸水性指数、膨胀势、各糊化特征值显著增大,水溶性指数明显降低,低物料水分形成的凝胶品质较好;随螺杆转速升高,水溶性指数增大,吸水性指数和峰值粘度、谷值粘度、衰减值稍降低,膨胀势先增大后减小,转速越高的苦荞粉的凝胶品质越好。综合而言,物料水分变化对挤压苦荞粉的各理化性质影响最大。吸水性指数和水溶性指数与糊化特性、凝胶特性都有显著相关性(P0.05);膨胀势与糊化特性极显著正相关(P0.01),与凝胶特性没有显著相关性。

Effect of extrusion processing on the physicochemical properties of tartary buckwheat flour

In order to clarify the effect of extrusion processing technology on the physicochemical properties of tartary buckwheat flour, the influence of the different extrusion temperature, material moisture and screw speed to the water absorption index, water solubility index, swelling power, pasting and gel properties of extrusion tartary buckwheat flour was studied. The results showed that: compared to the unextruded tartary buckwheat flour, the extrusion buckwheat flour at 30 °C water bath has a better water absorption and water solubility, whlie the water solubility in water bath at 100 °C increased, the water absorption decreased, swelling power, pasting and gel characteristic values increased significantly. With extrusion temperature increase, the water absorption index, water solubility index and swelling power of the extrusion tartary buckwheat flour changed little, but peak viscosity and attenuation value increased, trough viscosity and setback value decreased, the quality of gels become better; with the moisture content increase, the water absorption, swelling power and the pasting characteristic value increased obviously, water solubility reduced significantly, and quality of the gel formation in low moisture content was good; with the screw speed increase, water solubility increased, but the water absorption, peak viscosity, trough viscosity and attenuation value reduced slightly, swelling power increased first and then decreased, and gel quality of the higher screw speed tartary buckwheat flour is better. Overall, the greatest impact on the properties of extrusion buckwheat flour was the material moisture. Water absorption index and water solubility index were significantly correlated with pasting properties and gel properties (P <0.05). The swelling power and pasting properties were significantly positively correlated(P <0.01), and there was no significant correlation between the swelling power and gel properties.